8,196 research outputs found
Accurate, rapid identification of dislocation lines in coherent diffractive imaging via a min-max optimization formulation
Defects such as dislocations impact materials properties and their response
during external stimuli. Defect engineering has emerged as a possible route to
improving the performance of materials over a wide range of applications,
including batteries, solar cells, and semiconductors. Imaging these defects in
their native operating conditions to establish the structure-function
relationship and, ultimately, to improve performance has remained a
considerable challenge for both electron-based and x-ray-based imaging
techniques. However, the advent of Bragg coherent x-ray diffractive imaging
(BCDI) has made possible the 3D imaging of multiple dislocations in
nanoparticles ranging in size from 100 nm to1000 nm. While the imaging process
succeeds in many cases, nuances in identifying the dislocations has left manual
identification as the preferred method. Derivative-based methods are also used,
but they can be inaccurate and are computationally inefficient. Here we
demonstrate a derivative-free method that is both more accurate and more
computationally efficient than either derivative- or human-based methods for
identifying 3D dislocation lines in nanocrystal images produced by BCDI. We
formulate the problem as a min-max optimization problem and show exceptional
accuracy for experimental images. We demonstrate a 260x speedup for a typical
experimental dataset with higher accuracy over current methods. We discuss the
possibility of using this algorithm as part of a sparsity-based phase retrieval
process. We also provide the MATLAB code for use by other researchers
Cereal variety trials 1955-56
As an important step in the work of bringing new and improved cereal varieties to West Australian farmers, variety trials are carried out each season on the six wheatbelt research stations in this State. This provides a comparison of the performance, under actual field conditions, of recently produced varieties against those now in general cultivation
Dietary aflatoxin exposure and impaired growth in young children from Benin and Togo: cross sectional study
Fetal and early childhood environment, including the
nutritional status of the pregnant mother and the
infant, are considered critical for growth and risk of
disease in later life. Many people in developing coun
tries are not only malnourished but also chronically
exposed to high levels of toxic fungal metabolites
(mycotoxins). One family of mycotoxins, the aflatoxins,
are carcinogenic and immunotoxic and cause growth
retardation in animals. Aflatoxins contaminate staple
foods in West Africa, particularly maize and ground
nuts, as a result of hot, humid storage conditions that
promote fungal growth. High exposure to aflatoxins
occurs throughout childhood in the region, suggest
ing that growth and development could be critically
affected.We assessed exposure to aflatoxins in relation
to anthropometric measures in children in Benin and
Togo
Quantum Spin Lenses in Atomic Arrays
We propose and discuss `quantum spin lenses', where quantum states of
delocalized spin excitations in an atomic medium are `focused' in space in a
coherent quantum process down to (essentially) single atoms. These can be
employed to create controlled interactions in a quantum light-matter interface,
where photonic qubits stored in an atomic ensemble are mapped to a quantum
register represented by single atoms. We propose Hamiltonians for quantum spin
lenses as inhomogeneous spin models on lattices, which can be realized with
Rydberg atoms in 1D, 2D and 3D, and with strings of trapped ions. We discuss
both linear and non-linear quantum spin lenses: in a non-linear lens, repulsive
spin-spin interactions lead to focusing dynamics conditional to the number of
spin excitations. This allows the mapping of quantum superpositions of
delocalized spin excitations to superpositions of spatial spin patterns, which
can be addressed by light fields and manipulated. Finally, we propose
multifocal quantum spin lenses as a way to generate and distribute entanglement
between distant atoms in an atomic lattice array.Comment: 13 pages, 9 figure
Oat trials and usage in the Wheatbelt, 1956
The increasing acreages planted to oats in the Western Australian wheat growing districts have been associated with the improvement of farms for the carrying of stock and the need for a convenient change crop from wheat. Production of coarse grains, both oats and barley, has substantially increased the total area of cereals grown annually in Western Australia since 1930
Oats and barley for the export market
Today, with the accumulation of large stocks of wheat due to marketing difficulties, more attention is being paid to growing two coarse grains,oats and barley. These are more readily saleable on the worlds markets, at a price which gives a reasonable return to the grower
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Chemical transport model ozone simulations for spring 2001 over the western Pacific:comparisons with TRACE-P lidar, ozonesondes, and Total Ozone Mapping Spectrometer columns
Two closely related chemical transport models (CTMs) employing the same high-resolution meteorological data (similar to180 km x similar to180 km x similar to600 m) from the European Centre for Medium-Range Weather Forecasts are used to simulate the ozone total column and tropospheric distribution over the western Pacific region that was explored by the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) measurement campaign in February-April 2001. We make extensive comparisons with ozone measurements from the lidar instrument on the NASA DC-8, with ozonesondes taken during the period around the Pacific Rim, and with TOMS total column ozone. These demonstrate that within the uncertainties of the meteorological data and the constraints of model resolution, the two CTMs (FRSGC/UCI and Oslo CTM2) can simulate the observed tropospheric ozone and do particularly well when realistic stratospheric ozone photochemistry is included. The greatest differences between the models and observations occur in the polluted boundary layer, where problems related to the simplified chemical mechanism and inadequate horizontal resolution are likely to have caused the net overestimation of about 10 ppb mole fraction. In the upper troposphere, the large variability driven by stratospheric intrusions makes agreement very sensitive to the timing of meteorological features
Multi-model simulations of the impact of international shipping on Atmospheric Chemistry and Climate in 2000 and 2030
The global impact of shipping on atmospheric chemistry and radiative forcing, as well as the associated uncertainties, have been quantified using an ensemble of ten state-of-the-art atmospheric chemistry models and a predefined set of emission data. The analysis is performed for present-day conditions ( year 2000) and for two future ship emission scenarios. In one scenario ship emissions stabilize at 2000 levels; in the other ship emissions increase with a constant annual growth rate of 2.2% up to 2030 ( termed the "Constant Growth Scenario" (CGS)). Most other anthropogenic emissions follow the IPCC ( Intergovernmental Panel on Climate Change) SRES ( Special Report on Emission Scenarios) A2 scenario, while biomass burning and natural emissions remain at year 2000 levels. An intercomparison of the model results with observations over the Northern Hemisphere (25 degrees - 60 degrees N) oceanic regions in the lower troposphere showed that the models are capable to reproduce ozone (O-3) and nitrogen oxides (NOx= NO+ NO2) reasonably well, whereas sulphur dioxide (SO2) in the marine boundary layer is significantly underestimated. The most pronounced changes in annual mean tropospheric NO2 and sulphate columns are simulated over the Baltic and North Seas. Other significant changes occur over the North Atlantic, the Gulf of Mexico and along the main shipping lane from Europe to Asia, across the Red and Arabian Seas. Maximum contributions from shipping to annual mean near-surface O-3 are found over the North Atlantic ( 5 - 6 ppbv in 2000; up to 8 ppbv in 2030). Ship contributions to tropospheric O3 columns over the North Atlantic and Indian Oceans reach 1 DU in 2000 and up to 1.8 DU in 2030. Tropospheric O-3 forcings due to shipping are 9.8 +/- 2.0 mW/m(2) in 2000 and 13.6 +/- 2.3 mW/m(2) in 2030. Whilst increasing O-3, ship NOx simultaneously enhances hydroxyl radicals over the remote ocean, reducing the global methane lifetime by 0.13 yr in 2000, and by up to 0.17 yr in 2030, introducing a negative radiative forcing. The models show future increases in NOx and O-3 burden which scale almost linearly with increases in NOx emission totals. Increasing emissions from shipping would significantly counteract the benefits derived from reducing SO2 emissions from all other anthropogenic sources under the A2 scenario over the continents, for example in Europe. Globally, shipping contributes 3% to increases in O-3 burden between 2000 and 2030, and 4.5% to increases in sulphate under A2/CGS. However, if future ground based emissions follow a more stringent scenario, the relative importance of ship emissions will increase. Inter-model differences in the simulated O-3 contributions from ships are significantly smaller than estimated uncertainties stemming from the ship emission inventory, mainly the ship emission totals, the distribution of the emissions over the globe, and the neglect of ship plume dispersion
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